"In order to multitask you need to suppress the old task and move on to a new task, a process that's called 'inhibitory processing.' Bilinguals have a lot of practice at switching back and forth between frames of reference, especially as they go from work to home, speaking a native language vs English. You can call that multitasking."
Does that suggest it might be possible for persons to train their mind to be better at multitasking?"
"Absolutely," Leber said. But it's not clear yet exactly how.
Not all multitasks have been created equal. The scientific literature is crammed with studies indicating that you really should stay off your cell phone when driving a car. Steve Yantis of Johns Hopkins University explained why in the Journal of Neuroscience.
"Directing attention to listening effectively ' turns down the volume' on input to the visual parts of the brain," Yantis said. In other words, it's hard to listen and look at the same time, but that's particularly true if the sound is from another person and is directed specifically at you, according to other studies.
Researchers at Cornell University found that there's little problem with listening to the car radio, but if two people are talking to you at the same time, pull over to the side of the road. It seems that when two streams of stimuli are similar in type -- as in two kids yelling from the back seat -- it's much more difficult to drive the car than if the only noise is from the radio, or from one other person.
With more and more research, we might someday know how to improve our abilities to do two things at once, and possibly even figure out when to schedule those most difficult tasks for the periods when our cognitive control systems are at their peak.
But it's doubtful we will ever be able to get those kids to shut up when we're approaching a dangerous intersection.